Which To Choose???

[Scrupplez]

Been lurking for quite some time, just never have had any input due to not being as experienced as most of the forum. So I have been trying to learn as much as I can before posting. Have only been handloading for ~4 years. Currently I load for 30-06, .270 Winchester and 6.5 Creedmore.

The question I have been studying, is which load to proceed with for my 6.5CM.

41.7 is pretty much dead center with only a 17FPS spread between 41.5 and 41.9 with a .62 inch 5 shot group. The group above and below the 41.7gr. charge are sub MOA as well. Concern would be the 13.8 SD.

41.8 very similar group size; however the SD is less than half. I just do not have the comfort level of a second sub MOA group above with the 42.9 charge.

OCW would point to the 41.7 as it is a larger window.

The Chrono method would point to 41.8 due to the SD

H4350 / CCI400 Primers / COL 2.2215 (Ogive reading) / Hornady 140 ELD-M / 4X Fired Lapua brass

5 Shot Average
Charge - 41.5 41.6 41.7 41.8 41.9
Speed FPS - 2730 2730 2737 2741 2747
SD FPS - 10.2 15.3 13.8 6.1 5.5
Group Inches - 0.79 0.8 0.62 0.65 1.1







What say the masses? Any input would be appreciated.

Scrupplez

 

[z7]

The difference between 41.7 and 41.8?

I get the sd #s and everything, but let’s be honest, how accurate is your scale? Most are .1 grain accurate which means your steps are within the margin of error

How many shots per “step” or per load?

Have you adjusted searing depth?

What is the purpose/main use of the load?

 

[Scrupplez]

z7,
Yes. I am withing the margin of error.
There are 5 shots per charge. Small data group on this firing, but have 2 other fire strings with similar data.
I am at maximum mag length. When/If, I do start seating depth adjustments I can only seat deeper.
Mostly shooting for fun and bragging rights with ranges out to 1,000 yards.
Will also be used for hunting coyotes at distances up 450ish tops.

 

[ArchAngelCD]

Concern would be the 13.8 SD.

To tell the truth unless you are shooting out to 800 meters of more I wouldn't worry about those SD numbers especially if it's the most accurate load.

Loading for 4 years make a you are from a novice. You could have posted a long time ago, no need to be an expert to add to the conversation. That's how we all learn. Welcome to posting on the forum.

 

[LiveLife]

The question I have been studying, is which load to proceed with for my 6.5CM ... 41.7 ... 41.8

What say the masses? Any input would be appreciated.

I would conduct repeated accuracy tests to see if the accuracy results are consistent.

Then after more accurate powder charge is identified, incrementally decrease the OAL to see if accuracy improves.

 

[Blue68f100]

I would test more around the 4.1-4.7 range. This looks more in the middle of the node. But if you can test in the 200-300 yrd range ( or longer if available) will help to evaluate them. You did not show your targets but were you getting your spreed vertical or horizontal or general grouping.


What length barrel and gun?

 

[Demi-human]

Perhaps a more accurate scale is in order? Then you could load the half betwixt the two!


How many groups of each charge weight were shot? One of each is an idea. Three gives real data. Obviously more is better! (Ah, you have more, good.)

I'd say you have a good grasp on where the window is for your rifle...

And all will come to nullity compared to holding a running coyote in the scope. Sneaky beasts.
Both are sub-minute, at this elevation and temperature and pressure. Though the environment may be much different in their actual use.

So, may I suggest a ceremonial coin flip? Find a nice one. Old, rare or exotic. Get a nice place to hold the festivities set up. Conduct the formalities and celebrate!

Go forth in confidence and load much more!

Knowing that the right one has been chosen in a scientific and reasonable manner.



Plus, if you don't post, I can't learn from you...

 

[Scrupplez]

I do believe I am going to load 25 each of 41.7 and 41.8. Shoot 'em and smallest average wins.

 

[ArchAngelCD]

I do believe I am going to load 25 each of 41.7 and 41.8. Shoot 'em and smallest average wins.

that is a good idea but be sure the charges are exact because I'm really not sure there will be a difference between the two. Maybe changing the COAL will yield more results.

 

[z7]

I do believe I am going to load 25 each of 41.7 and 41.8. Shoot 'em and smallest average wins.

is there any way you can make it blind? if you have any way to intruduce bias you might slightly influence the results.

maybe load them in two batches, keep them separate, have an unbiased 2nd party use a marker to color the head stamp of one batch but not the other, or two different colors.

also, chrono all 50 shots in two different batches.

you will then need to consider what happens if you have .1g over either charge, is there a point of impact change between the two charges? what about 41.9g? POI change? if I had to guess, the two charges will share a point of impact.

 

[Demi-human]

I will second a very precise weighing.

Because they only differ by less than one tenth of one percent by weight of the entire charge.

That is like the difference in pressure between the action being out in the open or in the shade, on a cloudy day.

However slight there is a difference. And I am not saying that it is wasted effort. But I would think that the barrel's accuracy window is a bit larger than that.

I was being humorous earlier. Now I think, we're it me, I'd choose the lower charge for any theoretical safety margin gained heading into the warmer spring hunting season. Knowing that it's six degrees today in Michigan and by mid-May it will be ninety. That's a long stretch for any powder...

 

[Scrupplez]

All of the charges listed above share a very close point of impact. Just a difference in group sizing and SD.

I will make all charges as close as mechanically possible within the margin of error for my scale. Kind of particular about that anyway.

All 50 will be chronoed with a Labradar and shot in 2 separate series.

COAL changes would be after this test.

I do not think pressure will be an issue as I have shot up to 42.6 grains with this load in September last year before I got a slight ejector mark. Temps were in the low 80's. Was told there were people finding a good load around 2800-2810, my weapon just would not get there.

It was in the mid 50's Saturday, so not quite the temp swing that is in Mi.

Will be a few weeks before I send them down range due to previously scheduled activities.

I have a total of 3 series of test now that show a pattern of 2730ish to 2740ish being a happy place for my barrel. Fairly low SD numbers and sub MOA groups.